// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "content/browser/histogram_message_filter.h"

#include "base/command_line.h"
#include "base/metrics/histogram_macros.h"
#include "base/metrics/statistics_recorder.h"
#include "content/browser/histogram_controller.h"
#include "content/common/child_process_messages.h"
#include "content/public/common/content_switches.h"

namespace content {

HistogramMessageFilter::HistogramMessageFilter()
    : BrowserMessageFilter(ChildProcessMsgStart)
{
}

bool HistogramMessageFilter::OnMessageReceived(const IPC::Message& message)
{
    bool handled = true;
    IPC_BEGIN_MESSAGE_MAP(HistogramMessageFilter, message)
    IPC_MESSAGE_HANDLER(ChildProcessHostMsg_ChildHistogramData,
        OnChildHistogramData)
    IPC_MESSAGE_HANDLER(ChildProcessHostMsg_GetBrowserHistogram,
        OnGetBrowserHistogram)
    IPC_MESSAGE_UNHANDLED(handled = false)
    IPC_END_MESSAGE_MAP()
    return handled;
}

HistogramMessageFilter::~HistogramMessageFilter() { }

void HistogramMessageFilter::OnChildHistogramData(
    int sequence_number,
    const std::vector<std::string>& pickled_histograms)
{
    HistogramController::GetInstance()->OnHistogramDataCollected(
        sequence_number, pickled_histograms);
}

void HistogramMessageFilter::OnGetBrowserHistogram(
    const std::string& name,
    std::string* histogram_json)
{
    DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
    // Security: Only allow access to browser histograms when running in the
    // context of a test.
    bool using_stats_collection_controller = base::CommandLine::ForCurrentProcess()->HasSwitch(
        switches::kStatsCollectionController);
    if (!using_stats_collection_controller) {
        LOG(ERROR) << "Attempt at reading browser histogram without specifying "
                   << "--" << switches::kStatsCollectionController << " switch.";
        return;
    }
    base::HistogramBase* histogram = base::StatisticsRecorder::FindHistogram(name);
    if (!histogram) {
        *histogram_json = "{}";
    } else {
        histogram->WriteJSON(histogram_json);
    }
}

} // namespace content
